Benzotriazole, mercaptobenzothiazole and tolyltriazole are well known copper corrosion inhibitors. For example, see U.S. Pat. No. 4,675,158 and the references cited therein. This patent discloses the use of tolyltriazole/mercaptobenzothiazole compositions as copper corrosion inhibitors. Also, see U.S. Pat. No. 4,744,950, which discloses the use of lower (C.sub.3 -C.sub.6) alkylbenzotriazoles as corrosion inhibitors, and corresponding EPO application No. 85304467.5.
U.S. Pat. No. 4,338,209 discloses metal corrosion inhibitors which contain one or more of mercaptobenzothiazole, tolyltriazole and benzotriazole. Examples of formulations containing benzotriazole and tolyltriazole and formulations containing mercaptobenzothiazole and benzotriazole are given.
Copending patent application U.S.S.N. 348,522 relates to the use of higher alkylbenzotriazoles as copper and copper alloy corrosion inhibitors, copending patent application U.S.S.N. 348,532 relates to the use of alkoxybenzotriazoles as copper and copper alloy corrosion inhibitors, and copending patent application U.S.S.N. 540,977 relates to the use of alkylbenzotriazole/mercaptobenzothiazole, tolyltriazole, benzotriazole and/or phenyl mercaptotetrazole compositions as copper and copper alloy corrosion inhibitors.
U.S. Pat. No. 4,406,811 discloses compositions containing a triazole such as tolyltriazole, benzotriazole or mercaptobenzothiazole, an aliphatic mono- or di-carboxylic acid and a nonionic wetting agent.
U.S. Pat. No. 4,363,913 discloses a process for preparing 2-aminobenzothiazoles and alkyl and alkoxy-substituted aminobenzothiazoles.
U.S. Pat. No. 2,861,078 discloses a process for preparing alkyl and alkoxy-substituted benzotriazoles.
U.S. Pat. No. 4,873,139 discloses the use of 1-phenyl-1H-tetrazole-5-thiol to prepare corrosion-resistant silver and copper surfaces. The use of 1-phenyl-5-mercaptotetrazole to inhibit the corrosion of carbon steel in nitric acid solutions is also known. See Chemical Abstract CA 95(6):47253 (1979).
The present invention relates to alkoxybenzotriazole compositions comprising a) a C.sub.3 -C.sub.12 alkoxybenzotriazole; and b) a compound selected from the group consisting of mercaptobenzothiazole, tolyltriazole, benzotriazole, substituted benzotriazoles such as chlorobenzotriazole, nitrobenzotriazole, etc. and 1-phenyl-5-mercaptotetrazole, and salts thereof and the use thereof as corrosion inhibitors, particularly copper and copper alloy corrosion inhibitors. These compositions form long-lasting protective films on metallic surfaces, particularly copper and copper alloy surfaces, in contact with aqueous systems, and are especially effective in high-solids water. Additionally, these compositions generally provide improved tolerance to oxidizing biocides such as chlorine and bromine.
The use of the instant blends of C.sub.3 to C.sub.12 alkoxybenzotriazoles and one or more of mercaptobenzothiazole, tolyltriazole, benzotriazole and 1-phenyl-5-mercaptotetrazole or related compounds provides fast passivation, allows the use of lower concentrations of expensive alkoxybenzotriazoles for effective durable (persistent) film formation, provides stable, chemically resistent corrosion protection and overcomes problems relating to the failure to obtain passivation by alkoxybenzotriazoles alone in high-solids water. The instant admixtures also allow for intermittent feed to cooling water systems.
As used herein the term "passivation" refers to the formation of a film which lowers the corrosion rate of the metallic surface which is being treated. "Passivation rate" refers to the time required to form a protective film on a metallic surface, and "persistency" refers to the length of time a protective film is present on a metallic surface when a corrosion inhibitor is not present in an aqueous system which is in contact with the coated metallic surface. Also, the term "high solids water" refers to water which contains dissolved solids in excess of about 1,500 mg/L. Dissolved solids include, but are not limited to, anions released from chlorides, sulfates, silicates, carbonates, bicarbonates and bromides; and cations such as lithium, sodium, potassium, calcium and magnesium.
The instant alkoxybenzotriazole/tolyltriazole, benzotriazole, mercaptobenzothiazole and/or phenyl mercaptotetrazole compositions, or the use thereof for corrosion control, are not known or suggested in the art.